Introduction to Dermatology 1 Flashcards

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1
Q

The skin arises due to juxtaposition of which two major embryological elements?

A

Epidermis and the Dermis

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2
Q

What does the epidermis originate from?

A

The ectoderm

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3
Q

What does the mesoderm come into contact with?

A

inner surface of the epidermis

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4
Q

What does the dermis originate from?

A

The mesoderm

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5
Q

What is the mesoderm essential for enducing?

A

The differentiation of epidermal structures

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6
Q

What is the epidermis formed as by week 5?

A

A single basal layer of cuboidal cells

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7
Q

What is the periderm?

A

A secondary layer of squamous, non-keratinizing cuboidal cells which sits on top of the basal layer of the epidermis

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8
Q

When does the periderm develop?

A

Week 5

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9
Q

What is the vernix caseosa?

A

A white waxy protective substance which covers the skin during the last trimester of fetal development

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10
Q

what is the stratum germinativum also called

A

stratum basale

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11
Q

What happens to the basal layer of cuboidal cells from week 20?

A

The stratus germinativum proliferate to form a multi-layered intermediate zone which consists of four more superficial strata

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12
Q

What are the four superficial strata called?

A

The Spinosum, granulosum, lucidum and corneum

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13
Q

Where is the stratum lucidum found?

A

On the palms of hands and the soles of feet

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14
Q

what is the purpose of rete ridges

A

increase the contact area between layers, enhancing adhesion

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15
Q

when do dermal papillae form

A

weeks 12-14

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16
Q

what are dermal papillae?

A

The thin top layer of the dermis (the inner layer of the skin).

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17
Q

in what layer does the division of cells in epidermis occur?

A

basal layer

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18
Q

when does the neurovascular supply in dermal papillae develop

A

weeks 12-14

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19
Q

What are rete ridges?

A

When the epidermal ridges protrude as troughs into developing dermis beneath

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20
Q

When does the development of hair follicles occur?

A

Between weeks 9-13

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21
Q

In which superficial stratum layer do hair follicles develop?

A

In the stratum germinativum

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22
Q

What is lanugo hair?

A

soft, feathery hair that can grow all over the body, most often on the back and shoulders.

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23
Q

What cells is the epidermis composed of?

A

Keratinocytes

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24
Q

How long does the progression from stratum basale to Stratum corneum take?

A

30-40 days

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25
Q

What is the order of cellular progression of cells in the epidermis?

A

Starts with basale - then Spinosum, Granulosum, Lucidum and finally Corneum

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26
Q

What process is accelerated in skin conditions like psoriasis?

A

The cellular progression from the basal layer

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27
Q

What happens to the morphology of the epidermal cells as they progress from basal layer to Stratum Corneum?

A

They become progressively flatter

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28
Q

What are the special features of the stratum corneum?

A

They lack nuclei or organelles

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29
Q

What does the filamentous cytoskeleton of keratinocytes consist of? - 3

A

Actin containing microfilaments
Tubulin-containing microtubules
Intermediate filaments (keratins)

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30
Q

What are the five roles of keratins?

A

Structural properties
Cell signalling
StressResponse
Apoptosis
Wound Healing

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31
Q

What are desmosomes?

A

Major adhesion complex in the epidermis which anchor keratin intermediate filaments to cell membrane and bridge adjacent keratinocytes - allowing tissue architecture

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32
Q

What do desmosomes provide the epidermis with?

A

Resilience -allow the withstanding of trauma

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33
Q

What are gap junctions?

A

Clusters of intercellular channels (connexons) which allow connections between cytoplasm of adjacent keratinocytes to allow ions and small molecule transport

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34
Q

What are gap junctions essential for? - 4

A

Cell synchronization
cell differentiation
cell growth
metabolic coordination

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35
Q

what is the role of adherens junctions?

A

Transmembrane structures that engage with actin skeleton for cell-cell adhesion and intracellular signalling

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36
Q

what do tight junctions do

A

regulate the passage of proteins and liquids across the cell monolayer

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37
Q

What is the primary roles of tight junctions? - 2

A

maintaining barrier integrity and cell polarity

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38
Q

what are melanocytes?

A

They are dendritic cells which distribute melanin pigment to keratinocytes

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39
Q

How does the number of melanocytes change between different ethnicities?

A

The number of melanocytes does not change, however the amount of pigment they produce does vary

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40
Q

What four other cells are present in the epidermis aside from keratinocytes

A

Melanocytes, Langerhans cells, Merkel cells and Mast cells

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41
Q

What are Langerhans cells?

A

Dendritic cells which are antigen presenting and found in the epidermis

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42
Q

What are Merkel Cells?

A

Mechanosensory receptors

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43
Q

What sits under the epidermis layer?

A

Basement membrane

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44
Q

What is the basement membrane also known as?

A

The dermal-epidermal junction

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45
Q

state the key proteins and glycoproteins found in the dermal-epidermal junction - 4

A

type 4 & 7 collagens, laminin and integrins

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46
Q

What is the dermal-epidermal junction composed of?

A

Proteins and glycoproteins

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47
Q

What is the role of the basement membrane? - 4

A

cell adhesion
cell migration
rete ridge formation
wound healing

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48
Q

What layer of the skin is under the basement membrane?

A

The dermis

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49
Q

where does the dermis arise from?

A

mesoderm

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50
Q

What are the two layers the dermis is split into?

A

Papillary dermis and Reticular dermis

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51
Q

What aspect of the dermis layer provides resilience?

A

The supporting ECM

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52
Q

Which layer of the dermis is closest to the epidermis?

A

The papillary dermis

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53
Q

Which dermal layer is highly vascular?

A

Papillary dermis

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54
Q

What is the reticular dermis composed of?

A

Dense connective tissue

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55
Q

Which dermal layer forms the bulk of the dermis?

A

The reticular dermis

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56
Q

What is the papillary dermis composed of?

A

Loose connective tissue

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57
Q

What is the papillary dermis composed of?

A

loose connective tissue

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58
Q

Which proteins are present in the dermis?

A

Collagen and elastin fibres (fibrillin and elastin)

59
Q

Which collagen types are present in the dermis?

A

Type 1 and Type 3

60
Q

What are the three glycoproteins found in the dermis?

A

Fibronectins, fibulin and integrins

61
Q

What do the glycoproteins found in the dermis do?

A

They facilitate cell adhesion and cell motility

62
Q

What is the ground substance found in the dermis composed of?

A

Glycosaminoglycan and proteoglycan

63
Q

What does the ground substance lie between?

A

The dermal collagen and elastic tissue

64
Q

What are the primary cells present in the dermis?

A

Fibroblasts

65
Q

What do fibroblasts do?

A

Make collagen

66
Q

What cells aside from fibroblasts are present in the dermis? - 5

A

Histiocytes, mast cells, neutrophils, lymphocytes and dermal dendritic cells

67
Q

What does the subcuteanous layer contain?

A

Connective tissue and fat

68
Q

What are melanocytes derived from?

A

The neural crest

69
Q

What are melanocytes derived from?

A

The neural crest

70
Q

Does the blood supply cross into the epidermis?

A

No

71
Q

Describe the vascular supply of the skin?

A

The blood supply runs deep - composed of superficial vascular plexus which runs in the dermis

72
Q

Which dermal layer has more vascular supply?

A

papillary dermis - the superficial dermal layer

73
Q

What is the innervation of the skin composed of?

A

Both sensory and autonomic components

74
Q

What two autonomic components are involved in the innervation of the skin?

A

Cholinergic and Adrenergic

75
Q

What is meant by eccrine?

A

Opens directly onto the surface of the skin

76
Q

What is meant by apocrine?

A

Apocrine sweat glands, which are usually associated with hair follicles, continuously secrete a fatty sweat into the gland tubule

77
Q

What innervation do apocrine glands receive?

A

Adrenergic

78
Q

What is a pilosebaceous unit?

A

A structure consisting of hair, hair follicle, arrector pili muscle and sebaceous gland

79
Q

Which areas of the skin receive more innervation than any where else? - 4

A

Face, extremities, genitalia and hands

80
Q

Describe the innervation found in the superficial dermis?

A

A branching network, often accompanying blood vessels which forms a mesh of interlacing nerves

81
Q

What are the two types of afferent nerve endings?

A

Corpuscular and free

82
Q

What type of receptors are found in free nerve endings

A

Non-encapsulated receptors

83
Q

What type of receptors are found in corpuscular nerve endings?

A

Encapsulated receptors

84
Q

Which layer of the skin are non-encapsulated receptors found in?

A

Epidermis

85
Q

Which layer of the skin are encapsulated receptors found in?

A

Dermis

86
Q

What are two examples of encapsulated receptors?

A

Pacinian and Meissners

87
Q

What is a Meissner corpuscle?

A

It is an encapsulated, unmyelinated mechanoreceptor

88
Q

Where are Meissner’s corpuscle located, and where are they most concentrated?

A

Located in the superficial dermis and most concentrated in thick, hairless skin eg finger pads and lips

89
Q

What do Meissner Corpuscles help to detect?

A

Light touch and slow vibration

90
Q

What is another name for Meissners Corpuscle?

A

Tactile Corpuscle

91
Q

What is a Ruffini Corpuscle?

A

A slow acting mechanoreceptor

92
Q

Where is the Ruffini Corpuscle found?

A

Deeper in the dermis

93
Q

What shape are Ruffini Corpuscles?

A

Spindle shaped

94
Q

What are Ruffini Corpuscles sensitive to?

A

Skin stretch

95
Q

Where are Ruffini Corpuscles found with the highest concentration?

A

Around fingernails

96
Q

What do Ruffini Corpuscle monitor?

A

The slippage of object

97
Q

What is a Pacinian Corpuscle?

A

An encapsulated, rapidly adapting mechanoreceptor

98
Q

What are Pacinian Corpuscle involved in sensing?

A

Deep pressure and vibration

99
Q

What is the shape of Pacinian Corpuscle?

A

Ovoid

100
Q

Where are Pacinian Corpuscle most commonly found?

A

In the dermal Papillae of hands and feet

101
Q

What is the Merkel Cell derived from?

A

A modified keratinocyte

102
Q

What are Merkel cells used to detect?

A

Light and sustained touch, pressure

103
Q

What are Merkel cells used to detect?

A

Light and sustained touch, pressure

104
Q

What layer of the epidermis are Merkel cells found?

A

Basal layer

105
Q

Where are Merkel cells most populous?

A

In fingertips

106
Q

Aside from fingertips, where else are Merkel cells found? - 4

A

In the palms, soles, and oral and genital mucosa

107
Q

What nerve ending helps to detect pain?

A

Noicoreceptors

108
Q

what nerve endings can detect touch and pressure - 4

A

ruffini, pacinian, free and merkel

109
Q

what nerve endings can detect vibration - 2

A

meissner and pacinian

110
Q

What nerve ending helps to detect temperature?

A

Thermoreceptors

111
Q

What three microbiota are found in the skin?

A

Bacteria, fungi and viruses

112
Q

What is the role of the microbiome of the skin?

A

Immune modulation and epithelial health

113
Q

What is the predominant bacteria found in the microbiome of skin? - 4

A

Actinobacteria, Firmicutes and Bacteroidetes and Proteobacteria

114
Q

Is the microbiome involved in disease?

A

Yes

115
Q

what are the 6 functions of the skin?

A

Immunological Barrier
Physical Barrier
Thermoregulation
Sensation
Metabolism
Aesthetic Appearance

116
Q

What are the important immune cells in regards to the skin functioning as a immune barrier

A

Langerhans cells

117
Q

what are sentinel cells?

A

cells in the body’s first line of defense

118
Q

Which cells acts as sentinel cells in the epidermis

A

The langerhans cells

119
Q

How do Langerhans cells act against infection?

A

They initiate the immune response to microbial threats by detecting PAMPs

120
Q

How are the dendritic processes of the Langerhans cells extended?

A

Through intercellular tight junctions to sample the outermost layer of the skin - stratum corneum

121
Q

Which cells do Langerhans cells promote the expansion and activation of?

A

Skin resident regulatory cells (Tregs)

122
Q

Which cells carry out immune surveillance in the dermis?

A

Tissue-resident T cells, macrophages and dendritic cels

123
Q

What are the two keratinocyte derived endogenous antibiotics that are involved in the innate immune defense against bacteria and viruses?

A

Defensins and Cathelicidins

124
Q

What does the cornified cell envelope and stratum coneum restrict?

A

Water and protein loss from the skin

125
Q

What is one of the most toxic substance which the skin acts as a barrier against?

A

UV

126
Q

How does the skin protect against UV-induced DNA damage?

A

Melanin helps prevent UV from actioning its mutagenic property

127
Q

How does subcutaneous fat act as a physical barrier?

A

It acts as a shock absorber, helps cushion trauma

128
Q

What happens when the skin loses the ability to restrict water and protein loss?

A

Leads to dehydration which can cause pre-renal failure and high-output cardiac failure

129
Q

What type of sweat does eccrine glands secrete?

A

Salty sweat

130
Q

Where are apocrine glands most commonly found?

A

In the axilla and groin

131
Q

How does the skin regulate heat loss?

A

Through vasodilation and vasocontriction in deep or superficial vascular plexuses

132
Q

Which glands are involved in the cooling effect?

A

Eccrine glands

133
Q

What happens to the superficial vascular plexuses when we want to lose heat?

A

Vasodilation

134
Q

How do we lose heat through vasodilation/constriction?

A

radiation

135
Q

Aside from thermoregulation, what are the glands also important in?

A

FLuid regulation

136
Q

Synthesis of what metabolic compound occurs partially in the skin?

A

Vitamin D

137
Q

What percentage of total body fat is stored in the subcutaneous fat?

A

80%

138
Q

How does subcutaneous fat have metabolic functions?

A

It acts as a calorie reserve

139
Q

Which hormone is found in the subcuteaous fat?

A

Leptin

140
Q

What does the hormone leptin do?

A

Acts on hypothalamus to regulate hunger and energy metabolism

141
Q

What occurs when you do not produce leptin?

A

You have an insatiable appetite, gain unnecessary amount of adipose tissue = fat

142
Q

What psychological impact can skin have?

A

Leads to feels of low self worth, feeling “ugly”, not wanting to get into romantic relationships, increased risk of suicide

143
Q

What skin condition can cause renal failure?

A

Transepidermal fluid loss

144
Q

what is the stratum germinativum also called

A

stratum basale